160 Memoirs of the Indian Museum,. [Vol. VII, 



disappear, and there only remains a slight internal thickening close to the edge. As 

 is usual in the shells of this genus, the external ornamentation is reproduced in the 

 interior of the shell in inverted relief, so that it is the sunken intervals or grooves 

 of the outer surface which assume the appearance of ribs on the internal walls. On 

 crossing the internal marginal swelling of the labrum, in those specimens in which 

 the apertural features are characteristically developed, each of these internal ribs 

 usually develops a pair of elongate denticulati ons or ridges which terminate externally 

 against the fimbriated digitations of the edge. Sometimes the most anterior internal 

 rib develops but a single denticulation or ridge, while frequently some of the broader 

 posterior internal ribs (corresponding to the broad posterior intervals of the outer 

 surface) may give rise to three denticulations, or, occasionally, to as many as four. 



The first whorl following the protoconch is dark brown, though not so dark as 

 the protoconch itself. It is not uniformly tinted, the depth of the colour decreasing 

 considerably towards the posterior margin. On the following whorl the broad spaces 

 between the primary ribs are usually of a reddish or purplish, or sometimes bluish 

 tinge, while the main ribs themselves are white or yellowish- white maculated with 

 yellowish-brown. The same scheme may be continued on the third whorl with a 

 paler tint for the internals, and may also extend over the entire body- whorl, the 

 intervals becoming still paler, until with increasing growth they may become quite 

 white. In certain cases, the ribs, over the whole body-whorl, may maintain the 

 appearance of white bands with yellow spots (as in the type of Dolium lischkeanum, 

 Küster), while in other instances their coloured decoration may gradually disappear, 

 and, when the colour of the intervals has likewise vanished, the entire body- whorl 

 may be white. In other instances, the yellow tinge of the maculations gradually 

 spreads along the intervening portions of the ribs until all the spots coalesce, and the 

 ribs assume the appearance of continuous yellow bands. When, as is frequently the 

 case, the intervals have become nearly or quite colourless, the general colour scheme 

 becomes reversed in this sense that the ribs, instead of appearing as light spotted 

 bands against a darker ground, become darker bands against a lighter ground. This 

 is the appearance exhibited by Kiener's Dolium fasciatum var. Lastly, there are 

 specimens in which the greater part of the shell is almost uniformly tinted of a rich 

 orange or burnt-sienna colour, deepening to brown towards the apex. In large 

 thoroughly adult specimens, the intercalary ribs assume the same maculated decora- 

 tion as the original primary ribs. The deeper internal portion of the aperture is of 

 a yellowish or brownish tinge. The columella, the thickened portions of the colu- 

 mellar lip and inner portions of the outer lip are white and porcellaneous. 



Dimensions. — -The following measurements refer to a series of specimens obtained 

 from the Andamans, with the possible exception of No. 7, the exact origin of which 

 is uncertain. No. 5 is from the South Andaman. 



(1) (2) (3) (4) 



Height . .. 122 mm. 95 mm. 72 mm. 61 mm. 



Thickness . . 99 „ 73 „ 57 „ 50 „ 



Height of spire 29 ,, 27 ,, 22 ,, 16 „ 



(5) 



(6) 



(7) 



54 mm. 



37 mm. 



34 mm 



38 „ 



28 „ 



28 „ 



15 „ 



10 „ 



8 „ 



